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Robert L Rubin
The inability to translate findings from studies performed in mouse models to the corresponding human condition is well known, especially those involving infectious, atherosclerotic, and other inflammatory diseases. We hypothesize that mice fail to a mount robust or adequate immune response to infectious agents because of physiologic effects of cold stress due to housing temperatures below the mouse thermoneutral zone (TNZ). This hypothesis was tested by comparing the immune response to the Francisella tularensis live vaccine strain in mice housed at a typical vivarium temperature, which is below the TNZ, with that of mice housed at a temperature near their TNZ...
December 1, 2017: Comparative Medicine
David J Gregory, Igor Kramnik, Lester Kobzik
The goals of this study were to i) define which host genes are of particular importance during the interactions between macrophages and intracellular pathogens, and ii) use this knowledge to gain fresh, experimental understanding of how macrophage activities may be manipulated during host defence. We designed an in silico method for meta-analysis of microarray gene expression data, and used this to combine data from 16 different studies of cells in the monocyte-macrophage lineage infected with 7 different pathogens...
December 2, 2017: FEBS Journal
Dario Pistone, Massimo Pajoro, Eva Novakova, Nadia Vicari, Cesare Gaiardelli, Roberto Viganò, Camilla Luzzago, Matteo Montagna, Paolo Lanfranchi
A molecular screening for tick-borne pathogens was carried out in engorged and in questing ticks collected in Verbano Cusio Ossola county, Piemonte region, Italy. Engorged ticks were removed from wild and domestic animal hosts. The most abundant and common tick species in the area was Ixodes ricinus (192 adults, 907 nymphs). Few individuals of Ixodes hexagonus (15) and Rhipicephalus sanguineus (7) were found among the ticks removed from domestic animals (46 examined ticks). The presence of Rickettsia spp., Borrelia burgdorferi sensu latu, Francisella tularensis and Coxiella burnetii was evaluated by PCR and sequencing in 392 individuals of I...
November 30, 2017: Experimental & Applied Acarology
Roland Felix Dreier, José Carlos Santos, Petr Broz
Recognition of pathogens by the innate immune system relies on germline-encoded pattern recognition receptors (PRRs) that recognize unique microbial molecules, so-called pathogen-associated molecular patterns (PAMPs). Nucleic acids and their derivatives are one of the most important groups of PAMPs, and are recognized by a number of surface-associated as well as cytosolic PRRs. Cyclic GMP-AMP synthase (cGAS) recognizes the presence of pathogen- or host-derived dsDNA in the cytosol and initiates type-I-IFN production...
2018: Methods in Molecular Biology
Deyu Tian, Akihiko Uda, Eun-Sil Park, Akitoyo Hotta, Osamu Fujita, Akio Yamada, Kazuhiro Hirayama, Kozue Hotta, Yuuki Koyama, Mika Azaki, Shigeru Morikawa
Francisella tularensis, which causes tularemia, is an intracellular and Gram-negative bacterium. F. tularensis has received significant attention in recent decades because of their history as biological weapons. Thus, the development of novel vaccines directed against tularemia has been an important goal. The attenuated F. tularensis strain δpdpC, in which the pathogenicity determinant protein C gene (pdpC) was disrupted by TargeTron mutagenesis, was investigated as a potential vaccine candidate for tularemia in the present study...
November 24, 2017: Microbiology and Immunology
G Hestvik, H Uhlhorn, T Jinnerot, S Åkerström, F Södersten, D Gavier-Widén
Tularemia caused by the bacterium Francisella tularensis is a zoonotic disease. Tularemia is a common disease in the hare, and as a game species can be an important source of infection for humans. In this study, hares diagnosed with tularemia were examined with the aim to investigate whether the muscle (meat) had any pathological changes and/or contained F. tularensis. Real-time PCR and/or immunohistochemistry (IHC) detected the bacteria in muscle samples from 40 out of 43 investigated hares. IHC showed that bacteria were few and most commonly located in the peri- and endomysium...
November 23, 2017: Epidemiology and Infection
Amy E Rohlfing, Kathryn M Ramsey, Simon L Dove
The alarmone ppGpp is a critical regulator of virulence gene expression in Francisella tularensis In this intracellular pathogen ppGpp is thought to work in concert with the putative DNA-binding protein PigR and the SspA protein family members MglA and SspA to control a common set of genes. MglA and SspA form a complex that interacts with RNA polymerase (RNAP) and PigR functions by interacting with the RNAP-associated MglA-SspA complex. Prior work suggested that ppGpp exerts its regulatory effects in F. tularensis indirectly by promoting the accumulation of polyphosphate in the cell, which in turn was required for formation of the MglA-SspA complex...
November 20, 2017: Journal of Bacteriology
Elisabeth O Lampe, Carl Zingmark, Julia I Tandberg, Ida Marie P Thrane, Espen Brudal, Anders Sjöstedt, Hanne C Winther-Larsen
BACKGROUND: Francisella noatunensis ssp. noatunensis (F.n.n.) is the causative agent of francisellosis in Atlantic cod and constitutes one of the main challenges for future aquaculture on this species. A facultative intracellular bacterium like F.n.n. exert an immunologic challenge against which live attenuated vaccines in general are most effective. Thus, we constructed a deletion in the F.n.n. clpB gene as ΔclpB mutants are among the most promising vaccine candidates in human pathogenic Francisella...
November 16, 2017: Vaccine
Tomasz Wolkowicz
Modern diagnostics is in general based on molecular biology methods. Nowadays sequencing-based methods, especially whole genome sequencing, are becoming increasingly important. Implementation of such methods into routine diagnostic of highly dangerous pathogens, like Bacillus anthracis, Francisella tularensis, Yersinia pestis, Ebola virus, MERS, Lassa virus etc. would be very helpful. The best diagnostic strategy would be the metagenomic sequencing directly from the clinical sample. Implementation of majority of currently available WGS platforms inside the BSL-3 or 4 laboratory is impractical because of the size of the equipment and time consuming wet lab part (e...
November 10, 2017: Briefings in Functional Genomics
Hanseul Oh, C-Yoon Kim, Chang-Hwan Kim, Gyeung-Haeng Hur, Ji Min Lee, Seo-Na Chang, Jae-Hak Park
Francisella tularensis (FT), a highly infectious pathogen, is considered to be a potential biological weapon owing to the current lack of a human vaccine against it. Tul4 and FopA, both outer membrane proteins of FT, play an important role in the bacterium's immunogenicity. In the present study, we evaluated the immune response of mice-humanized with human CD34+ cells (hu-mice)-to a cocktail of recombinant Tul4 and FopA (rTul4 and rFopA), which were codon-optimized and expressed in Escherichia coli. Not only did the cocktail-immunized hu-mice produce a significant human immunoglobulin response, they also exhibited prolonged survival against an attenuated live vaccine strain as well as human T cell in the spleen...
November 14, 2017: Journal of Microbiology and Biotechnology
Adem Keskin, Ahmet Bursali, David E Snow, Scot E Dowd, Saban Tekin
Ticks are among the most significant human-biting ectoparasites and they play a major role in transmission of many pathogenic agents to humans. In the present study, three species of Hyalomma ticks, Hyalomma aegyptium, H. marginatum and H. excavatum, were examined for the presence of zoonotic bacteria, both male and female ticks alike. Examination of microbial diversity with tag-encoded pyrosequencing indicates that H. marginatum and H. excavatum were more diversity rich than H. aegyptium. Although numerous pathogenic and non-pathogenic bacterial genera were detected, including Acidovorax, Bacillus, Bacteroides, Bdellovibrio, Clostridium, Curvibacter, Escherichia, Flavobacterium, Limnohabitans, Paenibacillus, Ralstonia, Sarcina, Sediminibacterium, Segetibacter Stenotrophomonas and Variovorax, the predominant zoonotic bacteria represented in these ticks were genera Borrelia, Francisella, and Rickettsia...
November 9, 2017: Experimental & Applied Acarology
Nora Madani, Philippe Giraud, Christiane Mendy, Cécile Colaneri, Emeline Cherchame, Moulay-Ali Cherfa, Céline Richomme, Anouk Decors, Guillaume Girault
Here, we report the complete genome sequences of three strains of Francisella tularensis subsp. holarctica (11-789-5S, 11-935-13S, and 11-930-9S), isolated from brown hares and a tick during a tularemia outbreak in France, where tularemia is endemic.
November 9, 2017: Genome Announcements
Hadjila Yanes, Aurélie Hennebique, Isabelle Pelloux, Sandrine Boisset, Dominique J Bicout, Yvan Caspar, Max Maurin
Tularemia is a zoonosis caused by the bacterium Francisella tularensis Its specific diagnosis remains based on serological methods, while detection of F. tularensis in clinical samples by culture or PCR is rarely obtained. The aim of the present study was to evaluate the performance of the SERION ELISA classic Francisella tularensis IgG and IgM tests (Virion/Serion GmbH Institute, Würzburg, Germany) and the VIRapid® Tularemia immunochromatographic (ICT) test (VIRCELL, Granada, Spain), compared to the in-house microagglutination (MAT) and indirect immunofluorescence (IFA) tests currently used at the French National Reference Centre for Francisella...
November 8, 2017: Journal of Clinical Microbiology
Alison J Scott, Julia Maria Post, Raissa Lerner, Shane R Ellis, Joshua Lieberman, Kari Ann Shirey, Ron M A Heeren, Laura Bindila, Robert K Ernst
Mass spectrometry imaging (MSI) was used to elucidate host lipids involved in the inflammatory signaling pathway generated at the host-pathogen interface during a septic bacterial infection. Using Francisella novicida as a model organism, a bacterial lipid virulence factor (endotoxin) was imaged and identified along with host phospholipids involved in the splenic response in murine tissues. Here, we demonstrate detection and distribution of endotoxin in a lethal murine F. novicida infection model, in addition to determining the temporally and spatially resolved innate lipid inflammatory response in both 2D and 3D renderings using MSI...
November 6, 2017: Proceedings of the National Academy of Sciences of the United States of America
G Brett Moreau, Aiping Qin, Barbara J Mann
Zinc is an essential nutrient for bacterial growth. Because host cells can restrict pathogen access to zinc as an antimicrobial defense mechanism, intracellular pathogens such as Francisella must sense their environment and acquire zinc in response. In many bacteria, the conserved transcription factor Zur is a key regulator of zinc acquisition. To identify mechanisms of zinc uptake in Francisella novicida U112, RNA sequencing was performed on wild-type and putative zur mutant bacteria. Only three genes were confirmed by quantitative RT-PCR as directly regulated by Zur and zinc limitation...
November 6, 2017: Journal of Bacteriology
Michal A Swiat, Sofia Dashko, Maxime den Ridder, Melanie Wijsman, John van der Oost, Jean-Marc Daran, Pascale Daran-Lapujade
Cpf1 is a new class II family of CRISPR-Cas RNA-programmable endonucleases with unique features that make it a very attractive alternative or complement to Cas9 for genome engineering. Using constitutively expressed Cpf1 from Francisella novicida, the present study demonstrates that FnCpf1 can mediate RNA-guided DNA cleavage at targeted genomic loci in the popular model and industrial yeast Saccharomyces cerevisiae. FnCpf1 very efficiently and precisely promoted repair DNA recombination with efficiencies up to 100%...
November 2, 2017: Nucleic Acids Research
Andrea S Varela-Stokes, Si Hong Park, Sun Ae Kim, Steven C Ricke
Interest in microbial communities, or microbiota, of blood-feeding arthropods such as ticks (order Parasitiformes, suborder Ixodida) is increasing. Studies on tick microorganisms historically emphasized pathogens of high medical or veterinary importance. Current techniques allow for simultaneous detection of pathogens of interest, non-pathogenic symbionts, like Coxiella-LE and Francisella-LE, and microorganisms of unknown pathogenic potential. While each generation of ticks begins with a maternally acquired repertoire of microorganisms, microhabitats off and on vertebrate hosts can alter the microbiome during the life cycle...
2017: Frontiers in Veterinary Science
Liat Bar-On, Hila Cohen, Uri Elia, Shahar Rotem, Adi Bercovich-Kinori, Erez Bar-Haim, Theodor Chitlaru, Ofer Cohen
Francisella tularensis is the intracellular bacterial pathogen causing the respiratory life-threatening disease tularemia. Development of tularemia vaccines has been hampered by an incomplete understanding of the correlates of immunity. Moreover, the importance of lung cellular immunity in vaccine-mediated protection against tularemia is a controversial matter. Live attenuated vaccine strains of F. tularensis such as LVS (Live Vaccine Strain), elicit an immune response protecting mice against subsequent challenge with the virulent SchuS4 strain, yet the protective immunity against pulmonary challenge is limited in its efficacy and longevity...
October 25, 2017: Vaccine
Shib Shankar Saha, Jin Suzuki, Akihiko Uda, Kenta Watanabe, Takashi Shimizu, Masahisa Watarai
Understanding the virulence and pathogenesis of human pathogens using insect models is an increasingly popular method. Francisella novicida, which is virulent in mice but non-pathogenic to immunocompetent humans, is widely used as an ideal candidate for Francisella research. In this study, we developed a silkworm (Bombyx mori) infection model for F. novicida by inoculating the hemocoels of silkworms with F. novicida. We found that silkworms died within 3-7 days of F. novicida infection. However, the deletion mutant of DotU, the core part of type VI secretion systems, failed to kill silkworm...
October 21, 2017: Microbial Pathogenesis
Lauren C Kinkead, Laura C Whitmore, Jenna M McCracken, Joshua R Fletcher, Brandi B Ketelsen, Justin W Kaufman, Bradley D Jones, David S Weiss, Jason H Barker, Lee-Ann H Allen
F. tularensis infects several cell types including neutrophils, and aberrant neutrophil accumulation contributes to tissue destruction during tularemia. We demonstrated previously that F. tularensis strains Schu S4 and LVS markedly delay human neutrophil apoptosis and thereby prolong cell lifespan, but the bacterial factors that mediate this aspect of virulence are undefined. Herein, we demonstrate that bacterial conditioned medium (CM) can delay apoptosis in the absence of direct infection. Biochemical analyses show that CM contained F...
October 23, 2017: Cellular Microbiology
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